There are various known devices and methods of obtaining concentrates from certain blood components. To obtain a platelet concentrate, for example, blood from a donor in an extracorporeal circulation is centrifuged and separated into its components. An example of a device for carrying out such a method is disclosed in German Patent Application No. 42 27 695.
Platelet concentrates are needed for treating thrombocytopenic patients. Although it is generally sufficient to separate leukocytes by centrifugation, leukocytes, which are capable of causing an immune response, are preferably eliminated in transfusions of foreign blood to prevent undesirable immune system reactions in a patient.
In addition to transfusion of foreign blood, there has been widespread use of intraoperative autotransfusion, where the patient's own blood is collected during the surgery and retransfused back into the patient. The advantage of transfusion of autologous blood is that it prevents the transmission of infectious diseases such as AIDS and hepatitis while also avoiding transfusion reactions due to biological incompatibility and immune system reactions. So-called whole blood transfusion methods, where the collected blood is merely subjected to particle filtration, and plasma separation/washing methods, which supply washed erythrocyte concentrates for reinfusion, are used in the field of intraoperative autotransfusion. An example of a known autologous blood transfusion device is described in International Patent Application No. WO 99/02269.
In transfusion of foreign blood, there is the risk of immune reactions, but immune reactions do not occur with autotransfusion (autologous blood transfusion). On the other hand, the possibility of physiological reactions cannot be ruled out because the leukocytes are traumatized and/or activated in collection. It has been found that tumor cells, which may result from the autologous blood transfusion, may be eliminated by leukocyte depletion filters. U.S. Pat. No. 5,744,047 describes a leukocyte filter which is also used for autologous blood transfusions.